#1 - Page 2

fivemack · 2019-12-13, 20:28

Quote:

Originally Posted by VBCurtis

As always, you can trade off specs for price; I don't think there is a magic CPU spec necessary for your desired tasks. 32GB is enough memory for most NFS matrices; only the very biggest need more, such as helping with Greg's 16e queue. Kriesel has written extensively about memory needs for mprime's ECM and P-1. For ECM pretesting related to NFS factorizations, a large B1 like 850M use on the order of 1-1.5GB per thread; again, 32GB is satisfactory even though you might not use every hyperthread for the large bounds all at once.

I found that ECM at the B1=850M level was significantly faster at -maxmem 3000 (2.5GB per thread) - moved 64GB from a broken bargainhardware machine into a working one so I can run all 32 hyper threads at 2.5GB per thread.

VBITS=256 linear algebra runs get a bit tight in 32GB (VIRT 29.644g RES 0.028t for the 37.8M one running at the moment) but if you're doing nothing else with the machine it'll do.

VBCurtis · 2019-12-13, 21:28

I ought to check my notes rather than rely on human memory for ECM memory use!
I concur- B1=850M is ~2.4-2.7GB/thread. B1=~300M is the one that is 1-1.5GB. The range of use is because memory use also depends on the size of the input number. So, an NFS-interested party doing ECM pretesting would have to balance t65-level ECM with smaller curves or other tasks if using 32GB memory.

A common workflow on one of these dual-socket machines is to run an NFS matrix on one socket, using 20-30GB, and ECM / P-1 / whatever else on the other socket. So, you'd want 32GB on *each* socket, 64GB total, to have maximum flexibility. You can surely do what you wish with 32, but 64 means you're not having to plan around memory use (often).

Such decision don't really matter for DDR3-era users, since ECC DDR3 is under $2/GB. Fill up to 64 or 96GB and get to work!

Xyzzy · 2019-12-13, 23:06

While the idea of retired "big iron" is appealing, for this experiment we are using off-the-shelf parts.

- We like to build stuff.
- The build will, for maybe a year or two, be reproducible.

If you all agree 64GB isn't too cramped then that opens up a lot of possibilities.

As far as core count and speed, is it better to get fewer fast cores or many slow cores?

FWIW, we plan to build the box that is a result of this thread's discussion.

We don't plan to put any GPUs in it.

Maybe the first step is to choose the chipset and CPU?

chalsall · 2019-12-14, 00:12

Quote:

Originally Posted by Xyzzy

FWIW, we plan to build the box that is a result of this thread's discussion.

What are you wishing to achieve?

A really responsive workstation, or a compute box capable of unusual work?

Possibly different targets.

Modern GUIs (Windows, Mac, Linux) absolutely love (and waste) RAM. Mostly because of lazy programmers. Open a few dozen terminals, a few score of browsers, and some PDFs, and suddenly you're swapping at 16GB of RAM.

IMO, the best first upgrade any workstation can receive is to max out the RAM. The "User Experience" will be dramatically improved. (Next is 1080P monitors; note the plural.)

On the other hand, maxing out RAM for compute doesn't make a whole lot of sense to me, except for specialized applications.

Prime95 / mprime do quite well with only 8GB or so of RAM for "good" P-1 work. (OMGs, I just wrote "only 8GB"...

)

Personally, whenever I need a large memory footprint I find it far less expensive to rent it "in the cloud" for however long I need it.

And I'm just talking the electrical costs; Capex considerations would blow the idea of having the kit locally totally out of the question.

FWTW.

kriesel · 2019-12-14, 00:51

Quote:

Originally Posted by chalsall

What are you wishing to achieve?

Good general guidance. I think you'd approve of his headless linux approach; see https://www.mersenneforum.org/showpo...30&postcount=8

chalsall · 2019-12-14, 01:09

Quote:

Originally Posted by kriesel

I think you'd approve of his headless linux approach; see

Sorry. Yeah. Need to slow down.

Mike's mention of 64GB spun me up. "No one will ever need more than 640K...

masser · 2019-12-14, 01:18

What do you think about this build?

A couple iterations of feedback/build-construction should help us find a build that checks all of your boxes.

Why no GPU? What's the budget?

Gordon · 2019-12-14, 01:24

Quote:

Originally Posted by Xyzzy

What is the current situation for "enthusiast" computers with lots of memory?

Is 128GB or 256GB of memory "affordable" yet?

I'm running 64gb on a win 7 Pro setup...just a shame that gmp-ecm blows up when it tries to access more than 16gb :-(

VBCurtis · 2019-12-14, 01:56

Quote:

Originally Posted by masser

What do you think about this build?

A couple iterations of feedback/build-construction should help us find a build that checks all of your boxes.

Nice! DDR4 cheap enough to consider upgrading, myself.
I'd double the disk capacity; NFS jobs can use 100GB each for relations + matrix files, and it stinks to have one crash/out of disk merely because the previous one hadn't been deleted yet.

masser · 2019-12-14, 03:02

Quote:

Originally Posted by VBCurtis

I'd double the disk capacity; NFS jobs can use 100GB each for relations + matrix files, and it stinks to have one crash/out of disk merely because the previous one hadn't been deleted yet.

Good to know. I was initially thinking of adding a 1TB SSD as storage, with the M2 as the boot/OS drive, but decided to see what others suggested.

Xyzzy · 2019-12-14, 13:33

Given that the computer will be on 24x7 for several years under full load, would spending a little more upfront on a more efficient PSU save money in the long run?

FWIW, this is our current computer:

Code:

CPU: Intel Core i7-9700K 3.6 GHz 8-Core Processor
CPU Cooler: Noctua NH-U12S 55 CFM CPU Cooler
Motherboard: Asus ROG Strix Z370-I Gaming Mini ITX LGA1151 Motherboard
Memory: Corsair Vengeance LPX 32 GB (2 x 16 GB) DDR4-3200 Memory 
Storage: Samsung 970 Pro 1 TB M.2-2280 NVME Solid State Drive
Video Card: NVIDIA GeForce GTX 1080 Ti 11 GB Founders Edition Video Card
Case: Phanteks Enthoo EVOLV ITX Mini ITX Tower Case 
Power Supply: SeaSonic PRIME Ultra Titanium 650 W 80+ Titanium Certified Fully Modular ATX Power Supply
Operating System: Microsoft Windows 10 Home Full - USB 32/64-bit
Monitor: Dell AW3418DW 34.1" 3440x1440 120 Hz Monitor
Keyboard: Logitech G Pro Wired Gaming Keyboard
Mouse: Logitech G Pro Wired Optical Mouse
UPS: APC BX1500G UPS

2019-12-14, 01:18	#18
masser Jul 2003 Behind BB 11111010010₂ Posts	What do you think about this build? A couple iterations of feedback/build-construction should help us find a build that checks all of your boxes. Why no GPU? What's the budget? Last fiddled with by masser on 2019-12-14 at 01:21

2019-12-13, 21:28	#13
VBCurtis "Curtis" Feb 2005 Riverside, CA 2·2,927 Posts	I ought to check my notes rather than rely on human memory for ECM memory use! I concur- B1=850M is ~2.4-2.7GB/thread. B1=~300M is the one that is 1-1.5GB. The range of use is because memory use also depends on the size of the input number. So, an NFS-interested party doing ECM pretesting would have to balance t65-level ECM with smaller curves or other tasks if using 32GB memory. A common workflow on one of these dual-socket machines is to run an NFS matrix on one socket, using 20-30GB, and ECM / P-1 / whatever else on the other socket. So, you'd want 32GB on each socket, 64GB total, to have maximum flexibility. You can surely do what you wish with 32, but 64 means you're not having to plan around memory use (often). Such decision don't really matter for DDR3-era users, since ECC DDR3 is under $2/GB. Fill up to 64 or 96GB and get to work!

2019-12-13, 23:06	#14
Xyzzy Aug 2002 21D3₁₆ Posts	While the idea of retired "big iron" is appealing, for this experiment we are using off-the-shelf parts. - We like to build stuff. - The build will, for maybe a year or two, be reproducible. If you all agree 64GB isn't too cramped then that opens up a lot of possibilities. As far as core count and speed, is it better to get fewer fast cores or many slow cores? FWIW, we plan to build the box that is a result of this thread's discussion. We don't plan to put any GPUs in it. Maybe the first step is to choose the chipset and CPU?